Audio Transducers and Buzzers

Audio transducers and buzzers are used in electronic equipment, toys and various warning devices as sounding components. They can be either electromagnetic or piezoelectric in operation. Electromagnetic transducers generate either a single continuous sound or intermittent tones and are available with either self-contained or external drive circuitry. Piezoelectric transducers include a metal plate that vibrates with the expansion or contraction of a piezoceramic element. Some audio transducers can transmit signals, some can receive signals, and some can both transmit and receive signals.

Audio transducers and buzzers vary according to tone, frequency, and sound pressure. Some devices have an alarm with a continuous tone, while others have an alarm with a pulsed or non-continuous tone. The frequency measures the number of events or cycles that occur in a time period, usually one second, in Hertz (Hz). The sound pressure level (SPL) measures the loudness or volume in decibels (Db). A 10 Db increase in SPL represents a doubling in volume. In terms of electrical specifications, audio transducers and buzzers also vary by operating voltage rating, maximum operating current, and operating temperature.

There are several ways to terminate audio transducers and buzzers. Some devices use pre-wired leads or screw terminals. Others use multi-pin connectors called PC pins or plugs called quick connects. Solder tabs are flat pieces of metal to which operators can solder wires. Surface mount technology (SMT) connects the element to the surface by wave soldering, but does not use terminations.

There are several ways to mount audio transducers and buzzers. Panel mounted devices have a partially threaded body, a matching nut, and can be either flush or flange. Screw-down devices have flanges with holes. Socket mounted devices plug into a receptacle, typically an integrated circuit (IC). Surface mounted components are soldered to a flat pad on the face of a printed circuit board. Typically, this pad is coated with a paste-like formulation of solder and flux. With careful placement, components mounted in this way remain in place until elevated temperatures, usually from an infrared oven, melt the paste and solder the mount’s flat terminals to the circuit board’s pad.   

Some audio transducers and buzzers are programmable, provide volume control, or include a visual alarm to alert employees who work in areas with high noise levels. Internally driven transducers use self-contained circuitry with inductively coupled coils, and produce an average sound output of 85 Db or 10 cm/min. Externally driven transducers have a single coil and a magnetic circuit composed of a permanent magnet, an iron core, a highly permeable metal disk, and a vibrating diaphragm. 

There are a variety of applications for audio transducers and buzzers. Examples include measuring equipment, industrial sensors, industrial equipment and machines, computers and peripherals, medical equipment, and audio and video equipment.

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